Construction of NCQDs/Ag3PO4/Ag composite with dual-channel charge transfer property for efficient photocatalytic degradation of ciprofloxacin

A novel ternary composite photocatalyst of nitrogen-doped carbon quantum dots (NCQDs)/tetrapods silver phosphate (Ag 3 PO 4 )/silver (Ag) nanoparticles was designed and fabricated. Kelvin probe force microscopy and in-situ irradiated X-ray photoelectron spectrum demonstrated the cooperative action between the S-scheme heterojunction and Schottky junction within this ternary composite system, which facilitate efficient dual-channel charge transfer and achieve high oxidation potential. Moreover, the incorporating of persulfate into the photocatalytic reaction system enhanced the capture of photogenerated electrons, while the generated SO 4 -· radicals further improved photocatalytic reaction efficiency. Consequently, the NCQDs/Ag 3 PO 4 /Ag photocatalyst exhibited remarkable photocatalytic performance for the removal of ciprofloxacin (CIP). The mineralization rate of CIP over NCQDs/Ag 3 PO 4 /Ag photocatalyst activated by persulfate was about 6.7 times greater compared to the bare Ag 3 PO 4 photocatalyst. Additionally, four potential pathways for the photocatalytic degradation of CIP were proposed utilizing the LC-MS analysis. Furthermore, this ternary composite photocatalyst not only demonstrated high cyclic stability but also exhibited robust photocatalytic activity in systems containing coexisting anions, cations or various natural water sources, thereby exhibiting its application potential for antibiotic degradation in real environmental settings.